Normal mode splitting of transmission spectrum for Fabry-Perot cavity containing metamaterials

Metamaterials are artificial structures that display properties beyond those available in naturally occurring materials, for instance, it can show negative permeability or negative refractive index made of ordinary materials. On the other hand, metamaterials are resonant materials in general and can be seen as the combination of the electric resonator and the magnetic resonator. Based on this background, the coupling of the cavity mode with the metamaterials in the linear region has been theoretically investigated. We find that magnetic resonators can induce normal mode splitting as the electric resonator does, and the normal mode splitting induced by the metamaterials containing both electric and magnetic resonators is larger than that by only electric resonator. When the resonant frequencies of the electric and the magnetic resonators have the opposite deviations from the cavity frequency, transmission spectrum shows a three-peak shape in which two normal mode-splitting peaks and one revived cavity mode. Of most interest is that the full width at half-maximum (FWAM) of the revived cavity mode is much narrower than that of the empty cavity under certain conditions. This provides a new way to improve the quality factor of the cavity without increasing the reflectivity of the cavity walls. (C) 2009 Optical Society of America